1. Field of the Invention
The present invention relates to a film image input method, more particularly to a film image input method wherein an image of a developed film for still photography is focused on an image sensor through a taking lens and image signals, which are transferred photoelectrically by the image sensor, are output to a TV monitor, whereby the image of the film is replayed on the TV monitor.
2. Description of the Related Art
Conventionally, a film image input system wherein a developed film for still photography is focused on an image sensor such as a CCD and an image of the film is transferred into image signals, thereafter, the image signals are output to the TV monitor and the image of the film is displayed, is disclosed in WO90/04301, Japan Patent Application Laid-Open No.5-75922, Japan Patent Application Laid-Open No.5-56345, Japan Patent Application Laid-Open No.5-22656 and the like.
WO90/04301 discloses a camera and a film image input system which use a photo film provided with a magnetic recording track, and Japan Patent Application Laid-Open No.5-75922 discloses a film image input system which uses a film cartridge wherein a developed film for still photography is wound round a single spool.
Japan Patent Application Laid-Open No.63-39267 discloses an image reading system wherein the sub scanning is moved continuously to read the image recorded on the film with a line sensor such as a CCD sensor (lines 16-18, left bottom column, page 1). And, this publication has given a description in that the density of the film image and the base density of the film are detected from the reading output which is understood by the pre-scanning of the image by the CCD before the main reading and then the threshold to the comparator 8 is set by the CPU 2 (lines 11-15, right upper column, page 2). That is, when the film image is read by the line sensor, the film image is pre-scanned to read information such as the brightness of the film image, and then, while main-scanning, the CCD output is quantized such as binarized by the threshold in accordance with the information.
Now, triacetylcellulose (TAC) or polyethylene terephthalate (PET) is used for the base of the conventional photo film. There is no problem when the photo film is normally used in a camera, however, when the photo film is used in the film image input system, there is a problem in that both of TAC and PET tend to have a winding peculiarity and there is another problem about the dynamic intensity of TAC. That is, when the film, which is loaded between the supplying side and the winding side, is supplied between the supplying side and the winding side, no winding peculiarity and a strong dynamic intensity (particularly, tear intensity) are required for the film. Particularly, there are problems in that the winding peculiarity, which is generated in a state that the film is stored in the film cartridge, is apt to cause a jamming during the supplying of the film and the insufficiency of the dynamic intensity is apt to cause film damage such as a tear while it is being supplied.
And, the film image input system described in WO90/04301 and the like uses a two-dimensional image sensor as an image sensor and the film is supplied one frame at a time intermittently, therefore, the supply speed is not a problem. However, as described in Japan Patent Application Laid-Open No.63-39267, when the film image, which is supplied continuously, is read by the line sensor, the supply speed of the film must be kept constant, and the image data can not be obtained at a real time like two-dimensional image sensor, therefore, a pre-scanning is needed before a main-scanning and the film must be supplied frequently and repeatedly.
Therefore, the photo film for the image reading system using a line sensor is required to be hard enough to have a winding peculiarity, to have a strong dynamic intensity and to bear being used repeatedly.